In the classic experiment, the bottle remains at rest on a flat surface, such as a table. The flame source is placed in the bottle's base, and the egg is set on the bottle's mouth. Gravity assists the egg in traveling though the vacuum. Inverting the bottle is one variable in the experiment that will allow a heat source, such as a candle, to be placed in the egg and cause it to be sucked up into the bottle. Bottle inversion also allows for extraction of the egg by forcefully blowing air into the bottle, which should push the egg out of the neck.
Although flame is required for successfully completing the egg-in-the-bottle experiment, its source is a variable that allows for comparison and discussion. Wooden matches are typically dropped into the bottom of the glass. It is also possible to light a small bit of paper or tissue and drop it into the glass instead of a match. Change the direction of the heat source by inserting two small birthday candles into the egg so the heat flows from the mouth of the bottle rather than the base.
The pressure buildup created inside the bottle by the flame's consumption of oxygen and the need for equilibrium to fill the bottle's vacuum is the reason the egg is able to travel through the bottle neck; however, the external environment is also working on the egg at the same time. Conduct several experiments in areas of different atmospheric pressure with a bottle that is upright then inverted. Use a stopwatch to determine how long it takes for the egg to travel completely into the bottle during each experiment. Compare and discuss the role played by the pressure variable in the experiment's success.
Anyone who has conducted the egg-in-a-bottle experiment knows that in some cases, the egg breaks, as it travels into the bottle, while other times it does not go in at all. The proportion of the egg's diameter to the bottle's diameter is an important variable in the experiment. Collect eggs of several different sizes and two containers, one with a slightly smaller mouth than the glass jar and the other with a larger mouth. Experiment with each egg size on the different containers. Observe what happens in each test and time how long the experiment takes. Draw conclusions about the size relationship necessary for the egg to make it to the bottom of the container without breaking.